/* 全局重置 + 设计系统 */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --brand-primary: #0b1a2f;
  --brand-accent: #e5b53c;
  --brand-accent-light: #f5d87a;
  --brand-glass: rgba(255,255,255,0.07);
  --brand-glass-border: rgba(255,255,255,0.12);
  --text-light: #f0f4fa;
  --text-muted: #b0c1d9;
  --card-bg: rgba(255,255,255,0.04);
  --shadow-lg: 0 20px 40px -12px rgba(0,0,0,0.5);
  --radius-card: 24px;
  --radius-btn: 40px;
  --transition: 0.3s cubic-bezier(0.2, 0, 0, 1);
}
[data-theme="light"] {
  --brand-primary: #f5f9ff;
  --brand-accent: #b8862c;
  --brand-accent-light: #dba43e;
  --brand-glass: rgba(0,0,0,0.03);
  --brand-glass-border: rgba(0,0,0,0.08);
  --text-light: #1a2636;
  --text-muted: #3f4e62;
  --card-bg: rgba(0,0,0,0.02);
  --shadow-lg: 0 20px 40px -12px rgba(0,0,0,0.15);
}
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', sans-serif;
  background: var(--brand-primary);
  color: var(--text-light);
  line-height: 1.6;
  transition: background 0.2s, color 0.2s;
  overflow-x: hidden;
}
h1,h2,h3,h4 { font-weight: 600; letter-spacing: -0.02em; }
a { color: var(--brand-accent); text-decoration: none; transition: opacity 0.2s; }
a:hover { opacity: 0.8; }
img, svg { display: block; max-width: 100%; height: auto; }
.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
.section { padding: 5rem 0; }
.glass-panel { background: var(--brand-glass); backdrop-filter: blur(4px); -webkit-backdrop-filter: blur(4px); border: 1px solid var(--brand-glass-border); border-radius: var(--radius-card); box-shadow: var(--shadow-lg); }
.card { background: var(--card-bg); border-radius: var(--radius-card); padding: 2rem; box-shadow: 0 4px 12px rgba(0,0,0,0.1); transition: transform 0.2s, box-shadow 0.2s; }
.card:hover { transform: translateY(-4px); box-shadow: 0 12px 28px rgba(0,0,0,0.25); }
.btn-accent { background: var(--brand-accent); color: #0b1a2f; font-weight: 600; padding: 0.75rem 2rem; border-radius: var(--radius-btn); border: none; cursor: pointer; transition: all 0.2s; display: inline-flex; align-items: center; gap: 0.5rem; }
.btn-accent:hover { background: var(--brand-accent-light); transform: scale(1.02); }
.section-title { font-size: 2.2rem; margin-bottom: 1rem; color: var(--brand-accent); }
.grid-3 { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 2rem; }
.grid-2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 2rem; }
.flex-center { display: flex; align-items: center; justify-content: center; }
/* 滚动动画 (默认隐藏) */
.reveal { opacity: 0; transform: translateY(30px); transition: opacity 0.7s ease, transform 0.7s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }
/* header */
.header { position: sticky; top: 0; z-index: 100; background: rgba(11,26,47,0.82); backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px); border-bottom: 1px solid var(--brand-glass-border); padding: 0.6rem 0; transition: background 0.2s; }
[data-theme="light"] .header { background: rgba(245,249,255,0.85); }
.header .container { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; }
.logo svg { width: 130px; height: auto; }
.nav { display: flex; gap: 1.5rem; align-items: center; flex-wrap: wrap; }
.nav a { color: var(--text-light); font-weight: 500; padding: 0.3rem 0; border-bottom: 2px solid transparent; transition: 0.2s; }
.nav a.active, .nav a:hover { border-bottom-color: var(--brand-accent); color: var(--brand-accent); }
.mobile-toggle { display: none; background: none; border: none; color: var(--text-light); font-size: 1.8rem; cursor: pointer; }
@media (max-width: 820px) {
  .nav { display: none; width: 100%; flex-direction: column; gap: 0.8rem; padding: 1rem 0; }
  .nav.open { display: flex; }
  .mobile-toggle { display: block; }
}
/* hero banner */
.hero { min-height: 70vh; display: flex; align-items: center; background: radial-gradient(ellipse at 20% 40%, #1e3555, #0b1a2f); padding: 4rem 0; }
[data-theme="light"] .hero { background: radial-gradient(ellipse at 20% 40%, #e3eaf5, #d0dcea); }
.hero-content { max-width: 700px; }
.hero h1 { font-size: 3.2rem; line-height: 1.2; margin-bottom: 1.5rem; }
.hero .highlight { color: var(--brand-accent); }
.hero p { font-size: 1.2rem; color: var(--text-muted); margin-bottom: 2rem; }
/* footer */
.footer { background: rgba(0,0,0,0.3); padding: 3rem 0 2rem; border-top: 1px solid var(--brand-glass-border); }
.footer-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 2rem; }
.footer a { color: var(--text-muted); font-size: 0.9rem; }
.footer small { color: var(--text-muted); }
/* dark mode toggle */
.theme-toggle { background: none; border: 1px solid var(--brand-glass-border); border-radius: 40px; padding: 0.4rem 1rem; color: var(--text-light); cursor: pointer; font-size: 0.9rem; display: flex; align-items: center; gap: 0.4rem; }
/* 数字动画 */
.countup { font-size: 2.4rem; font-weight: 700; color: var(--brand-accent); }
/* FAQ */
.faq-item { border-bottom: 1px solid var(--brand-glass-border); padding: 1.2rem 0; }
.faq-question { display: flex; justify-content: space-between; cursor: pointer; font-weight: 500; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height 0.4s ease; color: var(--text-muted); }
.faq-item.open .faq-answer { max-height: 400px; margin-top: 0.8rem; }
/* 轮播 (极简) */
.carousel { display: flex; gap: 1.5rem; overflow-x: auto; scroll-snap-type: x mandatory; padding: 1rem 0; }
.carousel-item { min-width: 280px; scroll-snap-align: start; }
/* 返回顶部 */
.back-top { position: fixed; bottom: 2rem; right: 2rem; background: var(--brand-accent); color: #0b1a2f; border: none; border-radius: 50%; width: 48px; height: 48px; font-size: 1.4rem; cursor: pointer; box-shadow: 0 4px 12px rgba(0,0,0,0.3); z-index: 99; transition: 0.2s; opacity: 0; pointer-events: none; }
.back-top.show { opacity: 1; pointer-events: auto; }
/* 搜索模拟 */
.search-sim { background: var(--brand-glass); border-radius: 60px; padding: 0.4rem 1.2rem; display: flex; align-items: center; gap: 0.5rem; border: 1px solid var(--brand-glass-border); }
.search-sim input { background: transparent; border: none; color: var(--text-light); outline: none; width: 140px; }
.search-sim input::placeholder { color: var(--text-muted); }
/* 响应式调整 */
@media (max-width: 600px) {
  .hero h1 { font-size: 2.2rem; }
  .section-title { font-size: 1.8rem; }
}